have been in their effect on human interests, as of relatively slight physical importance. The sounds of the eruptions were audible for a distance of no more than two hundred miles. In the case of Krakatoa, the explosions were heard two thousand miles from their source. The enormous loss of life is explainable on other grounds than the intensity of the eruptions:

"A glance at the position of St. Pierre in relation to the volcano which destroyed it shows that the city lay within four or five miles of the cone, and on the side whereto the prevailing winds would be likely to drive the vapor and ashes from the crater. The ash ejected appears to have been mainly of a coarse nature, and the quantity of volcanic bombs,-that is, masses of lava, which, whirling, take on a rudely spherical form, more than usually great in quantity. The falling ash apparently served to force the heated air and steam down upon the surface, so that it flowed over the town; while the bombs, -molten lava within, though hard crusted without, were as effective as hot shot in carrying

There are from three hundred to three hundred and sixty volcanoes on the globe. This estimate includes merely live volcanoes and volcanoes which within recent times have been in action. If we should count the many mountains scattered over the earth which show to-day signs of volcanic action in the more remote past, the estimate would have to be increased by many hundreds.

THE PACIFIC OCEAN GIRDLED BY VOLCANOES.

Volcanoes would seem to be arranged, with more or less symmetry, in belts circling the great oceans. A ring of fire surrounds the Pacific. Starting at the South Shetland Islands, several hundred miles south of Cape Horn, a belt of volcanoes extends up the west coast of South America, Central America, and North America; from Alaska it crosses the Pacific along the Aleutian Islands to Kamchatka; thence it follows the east edge of the Pacific through the Kurile Islands, Japan, Formosa, the Philippines, the Moluccas, the Solomon Islands, the North Hebrides, New Zealand, and finally ends in Mounts Terror and Erebus, on the Antarctic Continent. The volcanoes forming this great belt are in places ranged in chains, as along the west coast of Central America and in the Aleutian Islands; elsewhere they are separated by long distances, but nevertheless they would seem to have some connection with each other. Sometimes the line of volcanoes surrounding the Pacific is very narrow, as in Central America, and then again it broadens hundreds of miles, as in the western United States, where extinct volcanoes on the east edge of the belt are hundreds of miles from the ocean and distant from each other.

Within this great Pacific circle of volcanoes, twenty-five thousand miles in length, are many volcanic islands: the Ladrones, the Hawaiian Islands, with the famous Mauna Loa; the Galapagos, the Samoan Islands, as well as the Tonga and Fiji archipelagoes, and many smaller groups. The coral islands may be also classed as volcanic, as they rest in great part on volcanic foundations.

Eastward from the circle around the Pacific, a branch belt extends through Sumatra and Java. On the broken isthmus which ages ago joined Asia and Australia are over one hundred volcanoes, many of which are constantly belching forth mud, lava, or ashes. This is the great

focus of volcanic action of the earth.

VOLCANOES OF THE ATLANTIC REGIONS.

Round nearly three sides of the Atlantic basin volcanic districts are scattered with some apparent symmetry. In the far north, Hekla and nearly one score others separate the Atlantic from the Arctic Ocean. Stretching from Ice

land, from north to south, an irregular submerged ridge bears the volcanic mountains of the Azores, the Cape Verde Islands, Ascension, St. Helena, and Tristan da Cunha. On the west edge of the Atlantic are the volcanoes of the West Indies; but north or south of the Antilles there is not a single volcano on the east coast of America. The volcanic belt of the Mediterranean shore is prolonged to the mountains of Armenia and western Arabia. There are said to be some volcanoes in Tibet and Manchuria, but the explorer has not yet located them.

Elisée Reclus has drawn attention to the fact that the great centers of volcanic action in the western and eastern hemispheres are at exactly opposite ends of the globe-are at antipodes to each other and that these centers of activity are near the poles of flattening. They also flank, one on the west and one on the east, the immense circle around the Pacific.

Hekla, in Iceland, and Mauna Loa, in the Hawaiian Islands, simply pour forth masses of lava that flows like molasses. Vesuvius and Mont Pelée, on the other hand, represent the explosive type of volcanoes, to which also belong the volcanoes of the Andes and of Mexico.

PROF

WHAT THE ASTRONOMERS ARE DOING. ROF. SIMON NEWCOMB says, in his article in the July Harper's, that no field of science has seen a greater progress in the past forty years than astronomy, and he proceeds to show what the great astronomers of the world are doing just at present to carry this progress still further.

PHOTOGRAPHING THE SUN.

At Greenwich Observatory the sun has been regularly photographed every clear day for more than twenty years, with a view of determining the changes going on in its spots. More recently observations from India and Mauritius have been added, so that now it is a rare day which does not see at least one new photograph taken. The object of this work is to explain the cycle of change in the sun-spots which goes through a period of about eleven years. No one has been able to establish the cause.

ficial eye, which he called a bolometer, in which the optic nerve is made of an extremely thin strip of metal, so slight that one can hardly see it, which is traversed by an electric current. This eye would be so dazzled by the heat radiated from one's body that, when in use, it must be protected from all such heat by being inclosed in a case kept at a constant temperature by being immersed in water. With this eye Langley has mapped the heat rays of the sun down to an extent and with a precision which were before entirely unknown.

CATALOGUING THE STARS.

As there are about 100,000,000 stars discernible through modern telescopes, it is a large task to study every one of them, but astronomers are doing their best in assigning the proper position and arrangement of the greatest possible number in their study of the structure and extent of the universe. The great national observatories are working on a catalogue giving the precise positions of the brighter stars, and up to the present time about 200,000 visible in our latitudes have been catalogued. In the southern hemisphere, Sir David Gill, astronomer at the Cape of Good Hope, and other scientists are hard at work on the stars not visible in our latitudes.

In the mere matter of listing the stars there is an enormous amount of work. Four hundred thousand have been listed in the last half a century at the observatory at Bonn. Dr. Thorne, in the Argentine Republic, has listed a half million. As to the stars which it is impossible to handle individually, there is an association of observatories engaged in making a photographic chart of the sky on the largest scale. When the observatories all over the world have handed in their work, we shall have a picture of the whole sky, the labor of an entire generation of astronomers.

MEASURING THE DISTANCE OF THE STARS.

Most of the heavenly bodies are so far away that even the most expert astronomers find it impossible to measure their distance through the only means at hand, that is, the slight change in the direction of the star produced by the swing of the earth around its orbit,—and there are probably not yet a hundred stars of which the paral lax has been closely obtained.

Professor Newcomb tells of the wonderful perfection of the spectrograph, used to measure the speed of the stars approaching or receding. Our own moon is one of the enigmas of the astrono

earth's axis of revolution varied from time to time has been verified.

THE SUCCESS OF AMERICAN ASTRONOMERS.

"A fact which will appeal to our readers on this side of the Atlantic is the success of American astronomers. Sixty years ago it could not be said that there was a well-known observatory on the American continent. The cultivation of astronomy was confined to a professor here and there, who seldom had anything better than a little telescope with which he showed the heavenly bodies to his students. But during the past thirty years all this has been changed. The total quantity of published research is still less among us than on the continent of Europe, but the number of men who have reached the highest success among us may be judged by one fact. The Royal Astronomical Society of England awards an annual medal to the English or foreign astronomer deemed most worthy of it. The number of these medals awarded to Americans within twenty-five years is just about equal to the number awarded to the astronomers of all other nations foreign to the English. Of its fifty foreign associates chosen for their eminence in astronomical research, no less than fourteen are Americans.

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THE NEW STAR IN PERSEUS.

NE of the most remarkable discoveries of the year 1901, astronomers say, was that of the brilliant new star in the constellation Perseus. On the night of its discovery, February 21, this star was nearly as bright as the brightest of the stars of the Great Dipper; two evenings later it had become the brightest of all the stars in the sky. Since that time the new star has been slow. ly fading away.

WHAT CAUSED THE OUTBURST OF LIGHT? Several theories as to the sudden appearance of this new star are suggested in an article contributed to the Journal of Geography for May by Mr. Eric Doolittle, who says:

"It may be that it resulted from the collision of two dark suns, rushing toward each other under their mutual attractions with an inconceivable velocity. The impact would have been sufficient to vaporize and raise to incandescence much of the material of which the bodies are composed.

owners concerning the value of scientific forestry. The only difficulty is to find trained men to put the principles of forestry into effect. The worst error of the private owner in the unscientific treatment of the forest is his ignoring its productive capacity. Immature trees are not cared for, and the forest is not able to repro e itself. Mr. Price explains that practical foresti is always a compromise between what should be done for the good of the forest and what is necessary to do in order that the property may yield a fair return on the capital it represents.

THE YOUNG GROWTH IS WORTH SAVING.

The attempt of the national government to cooperate with private owners of forests was begun in the Adirondacks in 1898. It was based on a careful preliminary study on the ground, by which the financial soundness of lumbering spruce with a view to taking a second crop in the sme area, was established. In other words, it was found by measurements of the number of mature and immature spruce trees, and by a study of their habit and rate of growth, that the return from lumbering renders it profitable to protect spruce trees of less than merchantable diameter, and to favor the reproduction of the tree.

THE RULES OF SCIENTIFIC LUMBERING.

"It was found that the customary method of logging spruce seriously impairs the advantage of holding the logged-off area for a second crop, through its great attendant damage to small trees and young growth generally. It was, therefore, necessary to so modify this method that without encroaching too far upon present profits the productive capacity of the forest might be preserved. Rules were drawn up to govern lumbering, the main objects of which were the following:

The leaving of a sufficient number of seed bearing spruce in the forest to invite reproduction, and of those smaller trees which, although of merchantable size, can be harvested much more profitably when they have reached a larger diameter.

The elimination of all unnecessary waste of merchantable timber, as in high stumps, lodged trees left in the woods, and failure to run the logs well up into the tops.

The avoidance, wherever practicable, of damage to young growth.

It is believed that the application of these rules by a large paper company to its own lands in Maine is the strongest argument in their favor which has yet been made. The purpose and practice of forestry on lands of private ownership in the Adirondacks are fully described in Bulletin 26 of the Bureau of Forestry, Practi

cal Forestry in the Adirondacks," by Mr. Henry S. Graves, now director of the Yale Forest School.

PRACTICAL EXAMPLES FOR PRIVATE OWNERS.

"The cooperation which is now carried on between private owners and the Bureau of Forestry has been undertaken with the belief that example will prove more powerful than precept in the institution of improved methods upon private forest-lands. It is intended to provide practical examples which show that conservative lumbering not only leaves the forest in better condition than does ordinary lumbering, but that it is usually a sounder financial policy. There has been in this country a good deal of severe criticism of lumbermen and lumbermen's methods which has done the cause of forestry no good. The American lumberman will not modify his methods until he has been shown that it is profitable for him to do so.

THE FORM OF COÖPERATION.

"In the coöperation between the Bureau of Forestry and a private owner, the first point to be decided is whether the application of forestry will be profitable upon the forest-land in question. A preliminary examination is accordingly made by a forester, the result of which is embodied in a report to the owner. If the conditions be favorable, a working-plan is then made, should the owner desire it. This working plan is a comprehensive and detailed scheme for the manage. ment of the forest. It forecasts the profits from lumbering and the present yield of merchantable timber. It fixes the diameter limit to which trees shall be cut, and prescribes all modifications of ordinary logging methods which are practicable and profitable in hastening the production of a second crop. It states how large this second crop will be in a given number of years, estimates the cost to the owner of obtaining it, and sums up what will be the result of conservative forest management from a business point of view. The working-plan entails careful measurements of the stand of merchantable timber, and of the number and size of immature trees. It includes a thorough study of the habits and rate of growth of the local trees, and the effect of lumbering upon the forest, and of those modifications of ordinary methods which are both silviculturally and financially advisable. Based upon this study on the ground, the working plan is a plain statement of the most profitable way in which a forest may be handled for its own good and for the good of the owner."

Owners of wood-lots and forest lands, from a few acres to thousands of acres, all over the United States, are eagerly availing themselves of this valuable aid.